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Claim. In On two unconventional number theoretic functions and on some related problems (Calcutta Math. Soc. Diamond-cum-Platinum Jubilee Commemoration Volume, Part I (1984), 113–121; library card erdos_1984_two_unconventional_number_theoretic_functions_related), Erdős asks on p. 120 whether for $n>n_0(r)$ some element of an optimal admissible set must have more than $r$ prime factors, and states, right after his joint result with van Lint on $G(n)$, that the case $r=1$ is easy: for large $n$ an optimal set contains an element that is not a prime power. He adds that a simple computation, which he did not carry out, would find the largest $n$ for which every element of an optimal set is a prime power. No proof is given. The site credits the result to Erdős and van Lint. In the notation of Problem 879 this is the second question at $k=2$.

Covers. The second question at $k=2$ only.

Standing. Claimed: the result is stated without proof, and the volume is a society's commemoration volume, not a journal, so it is not listed as refereed. The site's credit on a problem it labels OPEN is commentary, not acceptance.

Depends on. No page of this wiki.